Charging small units

[josan6]

What is the correct way to charge a small commercial refrigerator, with cap tube instead of txv, no sight glass, no lpc?. I have started up units with sight glass and txv, but never this kind. Thanks for ideas.

[Wild Leg]

You usually weigh the charge in, per the rating plate.

[newbie223]

I too started with 1/2hp and bigger units. They all have a sight glass and txv. Name plate rating only give you the ideal info. When the condensing unit is remote, you may need to charge a little more. Here is the quick way to charge small units:
For capillary orifice units, you charge the units by the superheat.
For TXV units, you charge the unit by the subcooling.

I hope this will help you.

[rayr]

Anyone here have stones enough to tell him about the frostback to within 6" of the compressor procedure for domestics and small cap tube refers????? Been around for 50 years that I know of.

[R12rules]

Rayr, your right. But that doesnt always apply to the new stuff. Sorry to say.

Let's face facts! It just ain't like it used to be!!!

You charge the system til she is about down to design temp and you do this by weighing in the factory charge, on the nameplate.

Best method on small systems is using a dial a charge.
But you first have to get a conversion chart for the new blends.
Unless that is, you are using R-12, R-22 or R-502.

A typical tech using a typical digital weight scale and no background experience in fractional horse systems will mis-charge everything they touch!!!




I used to love charging a fractional horse sealed system, using the frost back method.
Those were the days.
You didnt need a scale of any kind.
Just a bottle of gas and your gages.
No temp meter, no dial a charge, no superheat or subcooling readings...


AND NO WORRIES!!!


All you had to do was make sure your ambient was correct for where the box was to be operating in!

if you charged the system based on frost back and you did so in a low ambient, then delivered the box to a customer who was in a higher ambient ... you had some sweat to be sure!

[len]

weigh it in and go from there,i work on lot of fractional stuff,use your gauges,they will tell you where you are supposed to be,make sure the condeser is very clean,i mean clean.

[condenseddave]

Originally posted by R12rules
A typical tech using a typical digital weight scale and no background experience in fractional horse systems will mis-charge everything they touch!!!

With no adverse effects on unit life or product temperature whatsoever....

[condenseddave]

Mrs. Mulligan, who didn't read the directions, or heed the warnings, will kill her new fridge faster by not cleaning the coil, than any tech could mis-charging it.

[selfemployed]

Originally posted by rayr
Anyone here have stones enough to tell him about the frostback to within 6" of the compressor procedure for domestics and small cap tube refers????? Been around for 50 years that I know of.

We were told to have frost 6" out of the accum. just before the scotsman MC machines went into harvest. I was told about the frostback method of charging small cap tube systems early on too. When the cabinet is at temp. it worked well.

[R12rules]

systems which have a charge of 16 oz. or less usually have less tolerance for an ounce over or under the correct amount.

I am not saying the average tech is incompetant. I happen to have a high regard to our tradesmen.

However, you wouldnt want me walking into your boiler room and adjusting the controls.
Nor would you want my advice on fixing your chiller.
I dont work on them things!
I havent been trained on those.
I havent spent years working with them.

Everyone has their specialty. Everybody has skills in certain areas.

It is a lot easier to charge a rack system than it is a fractional horse unit. In my opinion.


From my observations of watching men in the field I have seen guys not removing the schrader valve cores prior to doing their pressure test/ evacuation/ charging sequence.
Most argure about the benefits of tripple evacuation.
Many do not use a proper sized filter drier and hence undercharge the system. The better driers we are recomending hold a little bit more refrigerant than the thin pencil spun driers which come OEM on the systems.

And the new driers, once installed, are not oriented in a downward manner so as to provide a liquid seal leading into the cappilary tube.



Ya know, I have always been facinated by Commercial Refrigeration!
In class.... I was the Gung-Ho guy who wanted to build and service ice machines and walk in boxes.

And I used to think that since I was working and learning on fractional horse systems ... I was being hindered in my education.


But the truth of the matter is this... with some experience and a little bit of training .... a guy can be good at both.
But it is not a piece of cake!!!



Guys who never had formal education on the subject but are sucessful on fractional systems are the one's who have gained what they need thru EXPENSIVE trial & error over many years time!!!


Anyone who assumes you can ust waltz into a fractional sealed system and do magic without some training & experience on those little guys will also assume an A/C guy can walk into a walk in freezer and know what's goin on!
Or they will assume a low temp man will walk onto an A/C job where air balance is the issue and will right away understand what is necessary to fix the problem.

As you might recall, about a year ago I got back into some market work.
I asked a ton of questions here.
And this is even despite the fact that these were the same chain stores I had serviced in California back in 96'.
So it was not like starting from square one.

Yet I still needed a heads-up.

Everyone here told me it was straight forward ... but no one ever said it was a cake-walk.

And that is all I am ranting about here.


After being on this forum for the time I have been... I have developed a great deal of respect for people who do things I thought were simple and beneath me.
Like A/C service.

And I would hope that those here who are lurking and afraid to ask publically the questions which are stumping them ... that they would make the conscious effort to dig in deep and learn what they can about fractional horse sealed system service.

[len]

CLEAN IT JUICE IT,ADJUST IT,FORGET ABOUT IT.its not rocket science,althought i like to think anybody in the trades have a lot more savvy and commensense,and expertise,than the folks that design this stuff,and say oh yea it will work,keeep in mind they design or build it we keep it chugging along.